When deploying wireless communications networks, there is a balance between coverage and capacity. On the one hand, a deployment including a few large cells can provide great coverage but at a cost of reduced capacity. On the other hand, a deployment with many small cells creates better capacity and throughput, but may not provide the desired coverage. Hence, there is often a combination of larger cells to provide sufficient coverage with smaller cells to provide better capacity. However, when the cells get too small, wireless terminals moving in the network cause a great number of handovers which causes significant overhead. Moreover, providing coverage indoors using many small cells can be quite costly, with a radio base station for each such small cell.
One solution to these problems is to use Remote Radio Heads (RRHs), where several RRHs connected to the same radio base station share the same cell. In this way, a single radio base station can, e.g., provide coverage in different parts of an indoor environment (e.g., a building) by placing the RRHs appropriately. Moreover, a wireless device can move between the coverage of different RRHs while staying within the same cell, thereby avoiding handovers.
Against this backdrop, User Equipment (UE) is a core requirement in Enhanced-911 (E911) and other services provided in a wireless network. Standard and regulatory bodies such as the Third Generation Partnership Project (3GPP) and the Federal Communications Commission (FCC) have increased their location requirements on the precision of indoor UE location.
However, since a single cell is spanned by multiple RRHs, the granularity of location determination is quite large. This leads to insufficient positioning accuracy in locating wireless devices, leading to issues in complying with increased accuracy of positioning requirements for emergency calls such as those specified in E911 by the FCC Communications Security, Reliability, and Interoperability Council (CSRIC). Positioning is also beneficial for other types of services, such as for targeted location based messaging. Since the RRHs are often deployed indoors, satellite based positioning such as Global Positioning System (GPS) is often unavailable.
As such, there is a need for systems and methods for determining the location of wireless devices (e.g., UEs) in a distributed antenna system (e.g., a cellular network deployment utilizing multiple RRHs in a single cell, e.g., in an indoor environment).